// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2015 Google Inc. All rights reserved.
// http://ceres-solver.org/
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// Author: sameeragarwal@google.com (Sameer Agarwal)
//
// Purpose: See .h file.

#include "impl_loss_function.hpp"

#include <algorithm>
#include <cmath>
#include <cstddef>
#include <limits>

namespace ceres 
{
    void GemanMcClureLoss::Evaluate(double s, double rho[3]) const
    {
        const double sum = c2_ + s;
        rho[0] = c2_ * s / sum;
        rho[1] = std::max(std::numeric_limits<double>::min(), c2_ * c2_ / (sum * sum));
        rho[2] = - 2 * c2_ * c2_ / (sum * sum * sum);
    }

    void SurrogateGemanMcClureLoss::Evaluate(double s, double rho[3]) const
    {
        const double sum = mu_ * c2_ + s;
        rho[0] = mu_ * c2_ * s / sum;
        rho[1] = std::max(std::numeric_limits<double>::min(), mu_ * mu_ * c2_ * c2_ / (sum * sum));
        rho[2] = - 2 * mu_ * mu_ * c2_ * c2_ / (sum * sum * sum);
    }
}